The invention relates to a method of decoding frames which have been encoded digitally while using compression, in which the number of pixels to be treated per unit of time is fixed and a frame is divided into blocks, each block comprising several pixels in both the horizontal and vertical direction, the compression being based on processing of blocks transmitted sequentially. Each frame is formed of two fields and may be any of at least three types, viz. of the intraframe type, encoded in its own absolute values, i.e. without reference to other frames; predicted-type frames encoded with reference to a preceding frame whisk may be an intraframe or predicted frame; and frames of the bidirectional type encoded with reference to at least two other frames which are each intraframes or predicted frames. Certain pains of an intraframe or predicted frame and a frame of the bidirectional type are such that the intraframe or predicted frame serves for coding or decoding of the frame of the bidirectional type which must be displayed prior thereto, requiring a memory space for storing the frames which have just been decoded or are being decoded. The invention also relates to a device for performing this method. The invention is applicable to the digital television of standard definition or high definition.
The compression algorithms for frames having a low rate use temporal treatments which necessitate a considerable memory capacity. Known systems make use of memory control at the level of the frame. However, the use of this method is limited because the memory size required for this control makes use of an excessively large number of memory units.